Cleaning process



Patented Dec. 17, 1940 Delaadgnontoll.

.1. I... am: Deb, a corporation or N p mi 1' 5,1938, 7 8. aster 40mm. (cuss-s1) This invention relates to the removal of calcareous deposits and is more particularly directed to compositions and processes wherein calcareous deposits are dissolved employing sulfamic acid.

6 Calcareous deposits are found in widely varying relationsgfor instance as a scale in boiler tubes, as an eillorescence from the mortar on walls. as a deposit in dairy equipment, or as an obstruction to the now oi oil in oil wells. The

in removal of calcareous deposits presents considerable difliculty since to dissolve such materials with an acid such as hydrochloric acid frequently efl'ects considerable damage to underlying metal or surrounding material.

15 Now we have found that calcareous deposits may be dissolved and removed from undesired relations by the use of sulfamic acid. The use of sulfamic acid to remove calcareous deposits presents a number of advantages arising from the go fact that sulfamic acid can readily and safely be handled and from the fact that it is much less corrosive than acids heretofore used.

sulfamic acid is particularly advantageous for the reason that calcium sulfamate,-the product :5 of its reaction with calcium deposits, is relatively water-soluble and can easily be washed away. With acids such as sulfuric and phosphoric the products formed when calcareous deposits are dissolved are insoluble calcium compounds such a as -calcium sulfate and calcium phosphate and these reaction products are themselves dimcult to remove in some instances.

In the cleaning of wells to remove calcareous material, a sulfamic acid solution may be intro- '35 duced into the well in dilute or saturated solutions in any desired quantity. A saturated solution containing excess sulfamic acid in suspended form may be used in which event the solution strength will remain about the same until all of g the suspended sulfamic acid is dissolved. In this way a considerable amount of acid can be introduced in a relatively small volume of liquid without a sudden violent reaction followed by a rapidly decreasing activity as would result with acids 5 heretofore used. If desired, an inhibitor such as a cinchona bark alkaloid bark derivative, a pyridine derivative, or a substituted thiourea may be used in known manner.

Bulfamic acid is less corrosive than hydrochloric acid, for instance, and may be handled with considerably greater ease and with considerably less hazard than materials heretofore used.

sulfamic acid offers the further advantage that it can readily be handled in solid form in which a condition it does not require special facilities for transportation required for an acid such as hydrochloric. In some instances it will be found practical simply to dump solid sulfamic acid into a well, adding a suitable amount of water later if necessary. Using solid sulfamic. acid in this =6 manner the well casing at notime comes in contact with a corrosive medium.

I The removal of calcareous residues from boiler tubes presents a problem in some respects similar to the problem of well cleaning and it will be 10 found that sulfamic acid is admirably adapted to I this use. According to our invention we employ a sulfamic acid solution or suspension of the desired strength and this is pumped or allowed to run by gravity into boiler tubes which are encrusted with calcareous residue. After the sulfamic acid solution has remained in the boiler tubes long enough to loosen the boiler scale, the boiler tubes should then be flushed with water.

sulfamic acid used for cleaning calcareous 59 residues from boiler tubes may conveniently be used in conjunction with inhibitors as'above described.

Because of the relatively small installations treated andbecause of the relatively long treat- 2!; ing time required, it is particularly advantageous for the cleaning of boiler tubes to have a material which does not attack the metal of the boiler rapidly and which is not hazardous or difficult to handle. For these reasons sulfamic acid is ideally adapted to this use. It will also be observed that for other similar uses such as the re-' moval of. calcareous residues fromhot water heating systems, heat exchangers, and automobile radiators, sulfamic acid offers the same advantages.

'I'hecleaning of boiler tubes and other such equipment with sulfamic acid is further advantageous for the reason that the calcium sulfamate which results from the dissolving action 40 is highly water soluble, about sixty-seven parts dissolving in one hundred parts of water at 25 C. By reason of its great solubility the calcium sulfamate may easily be washed from boiler tubes, heat exchangers, and other such equipment. sulfamic acid may easily and effectively be used to remove calcareous residue from cements. Calcareous residues which are very objectionable form on brick walls, the calcareous 0 material eillorescing from the cement or mortar between the bricks. Calcareous residues on concrete structures and in other such relations may also be removed. with advantage by the use of sulfamic acid.

Sulfamic acid is much safer to use than acids such as hydrochloric acid heretofore used for this purpose and sulfamic acid is not as irritating to the hands of workmen using it as is muriatic acid. it w The removal of calcareous residues with sulfamic acid according-to our invention is particularly advantageous in the cleaning of dairy equipment. copper or copper alloys, for the most part, and is very readily damaged by the use of cleaning agents heretofore proposed. Sulfamic acid may easily and effectively be used to remove nilkstone from dairy equipment without appreciable damage to the equipment. It is particularly advantageous to follow the practice of our invention because of the ease and safety of handling sulfamic acid.

Sulfamic acid will also be found advantageous for the cleaning of equipment such as aluminum or tinware by reason of the fact that it reacts only slowly with aluminum or tin.

From the foregoing it will be understood that 4 sulfamic acid may advantageously be used in a Such equipment is constructed of to the art with respect to other materials for removing calcareous residues and deposits.

While we have shown certain illustrative compositions and processes it will be understood that without departing from the spirit of our invention those skilled in the art may readily devise numerous compositions and processes wherein sulfamic acid is employed for removal of calcareous deposits.

We claim:

1. In a process for removing calcareous deposits, the step-oomprising contacting such a deposit .with' suli'amic acid.

2. In-a process for the removal of a calcareous deposit from a location at which it has formed, the steps comprising applying an aqueous solution of sulfamic acid to the said deposit at least partially to dissolve said calcareous deposit, and then removing the resulting aqueous solution which contains the dissolved material from the said location.

3. A method of treating a well comprising introduclng a solution comprising sulfamic acid into said well to react with substances in fluid communication with said well.

4. A methodvof acidizing an oil well comprising forcing a solution comprising sulfamic acid into said well and into geological formations adjacent said well to react with and open up said geological formations. I 1

. Ell-HER K. BOLTON.

JAMES K. HUNT. 

